The head of Hong Kong’s journalist union has been arrested, weeks before he was due to leave for an overseas fellowship at Oxford University. Ronson Chan, the chair of the Hong Kong Journalists Association (HKJA), was arrested for allegedly obstructing a police officer and disorderly conduct in a public place. Channel C, the online news outlet Chan works for, said the veteran reporter was taken away by officers who asked to check his identity while he was reporting on a meeting of public housing flat-owners on Wednesday. Police said a…